Four-Channel Reading; Infrared-Blocking, Low-Pass Filter; Cross Section Of Infrared Cut, Low-Pass Filter - Canon EOS 5D Service Manual

３）Four-channel reading
As with the EOS 20D, 4-channel reading is performed per line (Fig. 002) so that the
continuous shooting speed can be as fast as 3 fps even with approx. 12.8 megapixels.
Also, the increase in power consumption caused by the 4-channel reading is held to an
absolute minimum. As with the EOS 20D, power consumption is reduced by decreasing
the output amp's power consumption, cutting off power to the output amp during long
exposures, and cutting off the standard power current driving the circuitry.
Fig. 002 Four-channel reading and image processing diagram
４）Infrared-blocking, low-pass filter
The infrared-blocking, low-pass filter basically
consists of an infrared-blocking filter, low-pass filter,
phase plate, and low-pass filter.
The EOS 20D's infrared-blocking, low-pass filter has
the same basic construction with an infrared-absorbing
glass and three crystal plates. However, the EOS 5D's
filter has one independent crystal plate which also
functions as the CMOS sensor package's cover glass
(Fig. 003).
This makes it unnecessary to have a relatively
expensive cover glass. Therefore, the cost is reduced
without affecting the infrared-blocking, low-pass filter's
performance.
A/D
conversion
and
front-end
processing
circuit
4-channel reading
2
Technical Information
DDR SDRAM
Memory
card
Dichroic mirror
(Reflects infrared rays)
Infrared-absorbing glass
Low-pass filter
(Separates image in
vertical direction)
Phaser layer
(Converts linear polarized
light into circular polarized light)
Low-pass filter
(Separates image in horizontal
direction)
Fig. 003 Cross section of infrared cut,
low-pass filter
CMOS
sensor